• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.606-613
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• 2010

This paper proposes a novel current-based maximum power point tracking (CMPPT) method for a single-phase photovoltaic power conditioning system (PV PCS) by using a modified incremental conductance method. The CMPPT method simplifies the entire control structure of the power conditioning system and uses an inherent current source characteristic of solar cell arrays. Therefore, it exhibits robust and fast response under a rapidly changing environmental condition. Digital phase locked loop technique using an all-pass filter is also introduced to detect the phase of grid voltage, as well as the peak voltage. Controllers of dc/dc boost converter, dc-link voltage, and dc/ac inverter are designed for coordinated operation. Furthermore, a current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. A 3 kW prototype PV PCS is built, and its experimental results are given to verify the effectiveness of the proposed control schemes.

• 전기의세계
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• v.19 no.4
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• pp.1-11
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• 1970

It is well known that solid-state devices like inverter and converter made by transistor and other semi-conductors are widely used for the purpose of motor speed control in industrial fields. This paper is devoted primarily to a study of Trial Manufacturing of Solid-state Frequency Converter by means of single-phase bridge-type SCR inverter. The principle of the trial product belongs to AC-DC-AC conversion system. The voltage to be impressed to the motor in case of speed control by frequency conversion method is necessary to be proportional to frequency. It also requires the frequency and voltage are independent to hte load variation. In order to meet above requests required to motor speed control., the trial product introduced the open loop system in the frequency setting and closed loop system in the voltage setting. The trial product showed the favorable performance characteristics in speed control of singlephase fractional horsepower motor from 45HZ through 80HZ.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.525-529
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• 2001

A pulse frequency control(PFM) method for single-phase SEPIC-type rectifier is described in this paper. In the SEPIC rectifier, a relationship between the output power and the respective switching frequency is investigated to establish the control scheme of PFM. The propsed control method is provided with a feed-forward control loop of the output load as well as a feed-back control loop of the output voltage. The simulation results show good dynamic responses and unity power-factor operation.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1211-1212
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• 2007

In the PV power system, output of the PV array must contain inherent ripples due to the single-phase inverter. So, the function of maximum power point tracking to increase the output efficiency of PV system is degraded. Therefore, to overcome this problem, this paper presents a control strategy for the reducing ripples of the PV array output in grid-connected photovoltaic power system. The proposed control system consists of two loops; the maximum power point tracking loop using the perturbation and observation method is used to calculate the reference solar array terminal voltage(Vref) for reducing ripples of the PV array output and the PI control loop is used to regulate the solar array output voltage according to the Vref. The performance of proposing control strategy is analyzed by means of the PSCAD/EMTDC simulation and experiment. As a result, we may obtain the high performance of the proposed control strategy.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.274-282
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• 2013

In this paper, a linear motor stroke controller using a phase lag filter and a single phase PWM inverter with a current controller has been implemented. In order to control the cooling capability of a refrigerator or an air conditioner in which linear compressors are applied, the piston speed should be controlled. The piston speed control can be obtained by adjusting the frequency or the stroke of linear motors. Generally, the frequency is fixed, for example, as 60Hz and the stroke is adjusted. The dynamic performance of linear compressors depends on how accurately the stroke or the piston position is controlled by the current applied. A linear motor piston position controller with a current control loop is proposed and verified via some simulation studies.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.2
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• pp.96-104
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• 2009

This paper proposes a single-phase Phase-locked loop (PLL) of the virtual two phase generator using full-order state observer, which is essential to find phase and frequency of the single-phase source. The conventional methods cannot remove the low-order harmonics included in source voltage, which influencesto whole PLL control system. The proposed algorithm separates fundamental wave from harmonics, and removes harmonics effectively. Therefore it generates only the fundamental wave. As it controls virtual voltage and input voltage together, it decreases steady-state error. From simulation and experimental results, the generated frequency by the proposed PLL which it plans, converges to the actual value, and the steady-state error is much reduced under given harmonic voltages. It is also confirmed that the proposed algorithm removed harmonics effectively and it generates only the fundamental wave.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.325-330
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• 2012

A single-phase PVPCS(photovoltaic power conditioning system) that contains a single phase dc-ac inverter tends to draw an ac ripple current at twice the out frequency. Such a ripple current may shorten passive elements life span and worsen output current THD. As a result, it may reduce the efficiency of the whole PVPCS system. In this paper, the ripple current propagation is analyzed, and two methods to reduce the ripple current are proposed. Firslyt, this paper presents notch filter with IP voltage controller to reject specific current ripple in single-phase PVPCS. The notch filter can be designed that suppress just only specific frequency component and no phase delay. The proposed notch filter can suppress output command signal in the ripple bandwidth for reducing output current THD. Secondly, for reducing specific current ripple, the other method is feed-forward compensation to incorporate a current control loop in the dc-dc converter. The proposed notch filter and feed-forward compensation method have been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control scheme.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.6
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• pp.49-57
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• 1992

This paper proposes a Intel 8097 single-chip microprocessor based instantaneous voltage control scheme of inverter for UPS(Uninterruptible Power Supply). There microprocessors are used to control the output voltage and frequency of the inverter, the synchronization with by-pass, and the switching of the static switch. And the status and operating conditions of UPS systems is monitored by micro processor. The inverter output voltage is controlled instantaneously with a double regulation loop so that it has very good dynamic response for the varying loads or nonlinear loads as a rectifier. And also, the software and hardware of control system is described. From simulation and experimental results, it is shown that the proposed scheme has very good performance.

• Smart Structures and Systems
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• v.11 no.6
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• pp.569-587
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• 2013

This paper evaluates the closed loop performance of the reaching law based discrete sliding mode controller with multisensor data fusion (MSDF) in real time, by controlling the first two vibrating modes of a piezo actuated structure. The vibration is measured using two homogeneous piezo sensors. The states estimated from sensors output are fused. Four fusion algorithms are considered, whose output is used to control the structural vibration. The controller is designed using a model identified through linear Recursive Least Square (RLS) method, based on ARX model. Improved vibration suppression is achieved with fused data as compared to single sensor. The experimental evaluation of the closed loop performance of sliding mode controller with data fusion applied to piezo actuated structure is the contribution in this work.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.74-80
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• 2013

This study describes structural reliability analysis of actively-controlled structure for which random vibration analysis is incorporated into the first-order reliability method (FORM) framework. The existing approaches perform the reliability analysis based on the RMS response, whereas the proposed study uses the peak response for the reliability analysis. Therefore, the proposed approach provides us a meaningful performance measure of the active control system, i.e., realistic failure probability. In addition, it can deal with the uncertainties in the system parameters as well as the excitations in single-loop reliability analysis, whereas the conventional random vibration analysis requires double-loop reliability analysis; one is for the system parameters and the other is for stochastic excitations. The effectiveness of the proposed approach is demonstrated through a numerical example where the proposed approach shows fast and accurate reliability (or inversely failure probability) assessment results of the dynamical active control system against random seismic excitations in the presence of parametric uncertainties of the dynamical structural system.